Pneumatic tool.



E. CURTI.

PNEUMATIC TOOL.

APPLICATION FILED MAY 6. 1912.

l 1 88, 907 .A Patented June 27,' 1916.

THB COLUMBIA PLANOGRAPH co., wAsHxNaToN, D. c.

lf FFO..

ERNESTO CURTI, 0F MILAN, ITALY.

PNEUMATIC TOOL.

Specification of Letters Patent.

Patented June 2?, 1916.

Application led May 6, 1912. Serial No. 695,376.

To all whom t may concern Be it known that I, ERNESTO Crnrrr, mechanic, subject of the King of Italy, resident of No. 17 Via Santo Spirito, Milan, in the Kingdom of Italy, have invented new and useful Improvements in Pneumatic Tools, of which the following is a specification.

The present invention has reference to pneumatically-actuated tools, and it comprehends, generally, an implement of the characterindicated having improved means for controlling-the supply of air to the tool-piston from the pulsator which operates the same, and, in particular, for decreasing the shock of recoil of said tool-piston, whereby the implement is-simpliied and is rendered efficient and easily transportable.

An embodiment of the invention is illustrated in the accompanying drawing, where- Figure 1 is a vertical section of the implement and its operating mechanism. Fig. 2 is a fragmental sectional view of the pulsator, the pistons therein being shown in a different position from that-in Fig. 1. Fig. 3 is a bottom-plan view of one end of the pipe which connects the two pulsator cylinders, showing the relief valve therein. Figs.A

l and 5 are front elevations of the two members of an admission valve with which one of the pulsator cylinders is equipped. Fig. 6 is a transverse sectional view of said admission valve. Fig. 7 is a detail perspective view of the above-mentioned relief valve and its arrangement with relation to the end of the connecting pipe.

` Within the upper portion of the pulsator, there are arranged, side by side, a return cylinder t and a driving cylinder le, which are closed at their tops by the cap 4of the pulsator, but which open at their bottoms into a chamber or reservoir c that is in constant communication with the atmosphere, the said cylinders it and 7a being separated from each other by the wall or partition d. The pistons m and 'n work in said cylinders, and are connected to cranks on the shaft b, and this shaft has a suitable connection with a motor, (not shown), from which it is rocked or oscillated, the cranks being set at 180 apart. Pipes g and p connect the cylinders z, and la, respectively, with the front and rear ends of the tool-cylinder o, wherein the tool-piston r works, this tool-cylinder being provided with a handle o. The toolpiston r actuates the loose tool s, as will be understood.

Above the pulsator, there is arranged an inverted U-shaped channel or pipe e, that directly communicates at one end with an opening t formed through the cap of said pulsator, this opening being located directly above the cylinder 7c. The other end of pipe e 1s enlarged or flanged, as best shown in F ig. 7, and is connected to the pulsator cap directly above lthe cylinder it; and. said cap, at that point, is formed with an opening t, which is directly in line with the pipe end, as shown in Figs. l and 2, and is adapted to be opened and closed by a relief valve f. The upper portion of this valve 7 has an airtight fit in pipe e, but its enlarged, lower portion fits loosely within the enlarged or flanged portion of pipe e, and is arranged to rest upon the pulsator cap, directly over opening t, so as to close the same, the said enlarged valve portion being appreciably smaller than the enlarged orflanged portion of pipe c, as will be seen from Figs. l, 2, 3 and?. The said enlarged pipe portion or end is cut away to form one or more relief openings e.

The driving piston n is hollow, as shown, and opens at its bottom into the chamber or reservoir c, while at its top it is provided with an admission valve g that consists of an upper disk and a lower cross-bar connected by the valve stem, the sealing of the opening in the head of the piston being accomplished only by the upper disk. Said valve g acts at atmospheric pressure, and controls communication between said chamber or reservoir c and the upper portion of cylinder 7c and, hence, the pipe e.

'Io provide for the admission of air to the pulsator cylinder 7L, a valve is arranged in the wall of said cylinder. This valve, as shown in Figs. 4, 5 and G, preferably consists of a fixed disk and a rotatable disk y, positioned face to face, with their centers or axes alining. The Xed disk a2, which forms part of the cylinder wall, is provided with a series of openings and the movable disk y is provided with a single opening y', the latter disk being operable from the exterior of the pulsator by a handle y2, so as to bring the opening y into registration with any one of the openings for the purpose of regulating the beginning of the air-admission in the cylinder with relation to the position of the piston.

The operation is substantially as follows z-Assuming that the parts are in the position depicted in F ig. l, and that the ,driving piston a is about to commence its down stroke, the valve g will open during this stroke, through the action of the suction created above piston n, so that the pipe eY and Ychambers 7s and 0 will be in free communication. As the stroke of the piston continues, air will flow into chamber from chamber c, for the reason that the latter chamber, as previously stated, is in constant communication with the atmosphere. The relief valve f will be lifted away from the opening t by the suction created in pipe e during the downward movement of said piston a, since suction is necessarily produced in said pipe e, notwithstanding the flow of air through the opening in said piston controlled by valve g, by reason of the fact that a great difference exists between the volume of cylinder 7c and that of pipe e, while a compressing action is being simultaneously exerted by piston m, which at that time is moving upward. During its upstroke, piston m forces part of the air above it out to the atmosphere both through the relief openings c and through the passage formed by the registration of the opening i/"with one of the openings m. The remainder`of the air in cylinder 72,- above piston m is forced under slight pressure through pipe Q into the tool-cylinder 0, in front of the tool-piston r. The latter is thus forced rea 1'- wardly by this slight pressure, aided by the suction created in pipe 29 during the downward movement of piston n, before a suflicient quantity of air has passed through valve g to overcome the suction in cylinder 7c and establish therein the atmospheric pressure. This slow return movement is possible, owing to the escape of air through the openings e', and the passage w', y above referred to, and serves toV lessen the recoil, as will be understood. At the conclusion of the movements just described, piston i?, starts on its working or up-stroke, and piston m on its return or down-stroke, During the upward movementof piston n, valve g is closed, and the air above said piston is forced under pressure through pipes e and p, against valve f and into the rear end of cylinder o, causing said valve f to close opening t and effecting thc percussive stroke of piston 1' against tool s. The downward movement of piston m creates suction in cylinder 7L and pipe g, with the result that the forward movement of piston r is facilitated by the withdrawal of the air in front thereof, and that valve j is held more firmly against its seat. At a certain point in this stroke, which point is determined by the position of the movable disk vy relative to the fixed disk a, the passage formed by the registering openings m', jl/ is uncovered by piston m, thereby admitting air into cylinder 71 and at the conclusion of the stroke the cycle of movements re-commences.

It will be observed from the foregoing, that the tool-piston is always acted upon at its opposite sides or faces simultaneously; onone side by a positive force exerted by the in-coming compressed air, and on the other side by a negative or suction force exerted by the withdrawal of the air. Also, it is to be observed that the rearward or return movement is produced by a force which is less than that produced during the previous working movement, this being due to the employment of the parts e, e and f.

I claim as my invention 1. A pulsator for'operating the tool-piston of a pneumatic tool, comprising, in combination, a pair of cylinders adapted to be connected with the opposite ends of the toolcylinder wherein said tool-piston works; a pair of pistons working in said cylinders, each cvlinder having an opening in the top thereof; an inverted U-shaped pipe leading from one cylinder opening to the other, said pipe having one end thereof formed with a relief opening; and a relief valve arranged 1n said pipe end to cover and uncover the opening in the adjacent cylinder top, said valve being controlled, as to its movements, by said pair of pistons, and comprising an upper portion having an air-tight fit in said pipe and a lower portion which is of greater diameter than the diameter of said cylindertop opening.V

2. A pulsator for operating the tool-piston of a pneumatic tool, comprising, in combination, a pair of cylinders arranged side by side and adapted to be connected with the opposite ends of the tool-cylinder wherein said tool-piston works; a pair of reverselyarranged pistons working Vin the pulsator cylinders, each pulsator' cylinder having an opening' in the top thereof; an inverted U- shaped pipe leading from one cylinder opening to the other, said pipe having one end thereof formed with a relief opening; and aV relief valve arranged in said pipe end to cover and uncover the opening in the adjacent cylinder top, said valve being controlled, as vto its movements, by said pair of pistons, and comprising an upper portion having' an air-tight fit in said pipe and a lower portion which is of greater diameter than the said cylinder-top opening. V

3. A pulsator for operating the tool-piston of a pneumatic tool, comprising, in combination, a' pair of cylinders adapted to be connected with the opposite ends of the toolcylinder wherein said tool-piston works; a

pair of pistons Working in the pulsator cylinders, each pulsator cylinder having an opening therein; a pipe leading from one and comprising a portion having an air- 10 tight lit in said pipe.

In testimony whereof I hereunto aiiix my signature in the presence of two Witnesses.

ERNESTO GURTI.

lVitnesses BALLO SixLvo'r'iI, J. P. DE ARANEISNL come of Eme patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

